I made a sample page that forwards to different pages depending on which radio button is selected. First the radio buttons' values have to have the page that you are forwarding to stored in them. Then you can check if the radio group is set after the form is submitted. Then you can just set the location to be the radio button value and it will forward. Here is the code for the page:
<?php
if(isset($_POST["RadioGroup1"])) {
header("Location: ".$_POST["RadioGroup1"]);
}
?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Untitled Document</title>
</head>
<body>
<form id="form1" name="form1" method="post" action="">
<p>
<label>
<input type="radio" name="RadioGroup1" value="untitled1.php" id="RadioGroup1_0" />
Page1</label>
<br />
<label>
<input type="radio" name="RadioGroup1" value="untitled2.php" id="RadioGroup1_1" />
Page2</label>
</p>
<p>
<label>
<input type="submit" name="button" id="button" value="Submit" />
</label>
<br />
</p>
</form>
</body>
</html>